US6311684B1 - Continuous wire saw loop and method of manufacture thereof - Google Patents

Continuous wire saw loop and method of manufacture thereof Download PDF

Info

Publication number
US6311684B1
US6311684B1 US09/467,510 US46751099A US6311684B1 US 6311684 B1 US6311684 B1 US 6311684B1 US 46751099 A US46751099 A US 46751099A US 6311684 B1 US6311684 B1 US 6311684B1
Authority
US
United States
Prior art keywords
wire
loop
work piece
diameter
weld
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US09/467,510
Inventor
John B. Hodsden
Jeffrey Burgess Hodsden
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DIAMOND MATERIALS TECH Inc
SNOW ACQUISITION CORP
Original Assignee
Laser Tech West Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US08/980,386 priority Critical patent/US6065462A/en
Application filed by Laser Tech West Ltd filed Critical Laser Tech West Ltd
Priority to US09/467,510 priority patent/US6311684B1/en
Application granted granted Critical
Publication of US6311684B1 publication Critical patent/US6311684B1/en
Assigned to LASER TECHNOLOGY WEST, LTD. reassignment LASER TECHNOLOGY WEST, LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HODSDEN, JEFFREY BURGESS, HODSDEN, JOHN B.
Assigned to LASER TECHNOLOGY WEST, LLC reassignment LASER TECHNOLOGY WEST, LLC CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: LASER TECHNOLOGY WEST, LTD.
Assigned to DIAMOND WIRE TECHNOLOGY LLC reassignment DIAMOND WIRE TECHNOLOGY LLC CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: LASER TECHNOLOGY WEST, LLC
Assigned to SNOW ACQUISITION CORP. reassignment SNOW ACQUISITION CORP. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DIAMOND WIRE TECHNOLOGY LLC
Assigned to DIAMOND WIRE TECHNOLOGY, INC. reassignment DIAMOND WIRE TECHNOLOGY, INC. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: SNOW ACQUISITION CORP.
Assigned to DIAMOND MATERIALS TECH, INC. reassignment DIAMOND MATERIALS TECH, INC. CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). Assignors: DIAMOND WIRE TECHNOLOGY, INC.
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23DPLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
    • B23D61/00Tools for sawing machines or sawing devices; Clamping devices for these tools
    • B23D61/18Sawing tools of special type, e.g. wire saw strands, saw blades or saw wire equipped with diamonds or other abrasive particles in selected individual positions
    • B23D61/185Saw wires; Saw cables; Twisted saw strips
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23DPLANING; SLOTTING; SHEARING; BROACHING; SAWING; FILING; SCRAPING; LIKE OPERATIONS FOR WORKING METAL BY REMOVING MATERIAL, NOT OTHERWISE PROVIDED FOR
    • B23D65/00Making tools for sawing machines or sawing devices for use in cutting any kind of material

Abstract

A closed loop wire saw loop, a method for making the closed wire saw loop, and an apparatus and method for slicing a work piece, in particular, a polysilicon or single crystal silicon ingot, utilizing a closed loop of diamond impregnated wire in which the work piece (or ingot) is rotated about its longitudinal axis as the diamond wire is driven orthogonally to it and advanced from a position adjoining the outer diameter (“OD”) of the ingot towards its inner diameter (“ID”). In this manner, the diamond wire cuts through the work piece at a substantially tangential point to the circumference of the cut instead of through up to the entire diameter of the piece and single crystal silicon ingots of 300 mm to 400 mm or more may be sliced into wafers relatively quickly, with minimal ‘kerf” loss and less extensive follow-on lapping operations. The closed wire saw loop is made by squaring and welding the wire ends together and then twice heat treating the weld at about 1500 F.

Description

This application is a division of the application Ser. No. 08/980,386, filed on Nov. 28, 1997.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to the field of an apparatus and method for accurately sawing a work piece into two or more sections. More particularly, the present invention relates to an endless wire saw and a method for making an endless wire saw for cropping and/or slicing crystalline ingots, such as relatively large diameter polysilicon and single crystal silicon ingots.
2. Description of the Related Art
The vast majority of current semiconductor and integrated circuit devices are fabricated on a silicon substrate. The substrate itself is initially created utilizing raw polycrystalline silicon having randomly oriented crystallites. However, in this state, the silicon does not exhibit the requisite electrical characteristics necessary for semiconductor device fabrication. By heating high purity polycrystalline silicon at temperatures of about 1400 degrees, a single crystal silicon seed may then be added to the melt and a single crystalline ingot pulled having the same orientation of the seed. Initially, such silicon ingots had relatively small diameters of on the order of from one to four inches, although current technology can produce ingots of 150 mm (six inches) or 200 mm (eight inches) in diameter. Recent improvements to crystal growing technology now allow ingots of 300 mm (twelve inches) or 400 mm (sixteen inches) in diameter to be produced.
Once the ingot has been produced, it must be cropped (i.e. the “head” and “tail” portions of the ingot must be removed) and then sliced into individual wafers for subsequent processing into a number of die for discrete or integrated circuit semiconductor devices. One method for cropping the ingot is through the use of a band saw having a relatively thin flexible blade. However, the large amount of flutter inherent in the band saw blade results in a very large “kerf” loss and cutting blade serration marks which must then be lapped off.
One technique of slicing a semiconductor ingot into wafers is the slurry saw. The slurry saw comprises a series of mandrels about which a very long wire is looped and then driven through the ingot as a silicon carbide or boron carbide slurry is dripped onto the wire. Wire breakage is a significant problem and the saw down time can be significant when the wire must be replaced. Further, as ingot diameters increase to 300 mm to 400 mm the drag of the wire through the ingot reaches the point where breakage is increasingly more likely unless the wire gauge is increased resulting in greater “kerf” loss. Importantly, a slurry saw can take many hours to cut through a large diameter ingot.
A much preferred technique for slicing an ingot into wafers is disclosed in copending patent application Ser. No. 08/888,952, filed Jul. 7, 1997 and entitled Apparatus and Method For Slicing A Workpiece Utilizing A Diamond Impregnated Wire, the disclosure of which is hereby incorporated by reference in its entirety. This technique is a method for slicing a work piece, in particular, a polysilicon or single crystal silicon ingot utilizing a length of diamond impregnated wire in which the work piece (or ingot) is rotated about its longitudinal axis as the diamond wire is driven back and forth orthogonally to the longitudinal axis of the work piece and advanced from a position adjoining the outer diameter (“OD”) of the ingot towards its inner diameter (“ID”). In this manner, the diamond wire cuts through the work piece at a point substantially tangential to the circumference of the cut instead of through up to the entire diameter of the piece. Through use of this technique, polysilicon or single crystal silicon ingots of 300 mm to 400 mm or more may be sliced into wafers relatively quickly, with minimal ‘kerf” loss and less extensive follow-on lapping operations.
There is no known continuous wire saw loop that can be used to make these extremely fine cuts. Consequently, the apparatus for sectioning a substantially cylindrical crystalline work piece with this technique uses a relatively long length of wire having a plurality of cutting elements affixed thereto which has both ends wrapped around a capstan which alternatingly rotates first in one direction and then an opposite direction, while the work piece rotates continuously in one direction or alternately in opposite directions to the movement of the wire. This technique and apparatus results in faster, finer cuts than the slurry saw can produce.
Laser Technology West, Limited, Colorado Springs, Colo., a manufacturer and distributor of diamond impregnated cutting wires and wire saws, has previously developed and manufactured a proprietary diamond impregnated wire marketed under the trademarks Superwire™ and Superlok™. These wires comprise a very high tensile strength steel core with an electrolytically deposited surrounding copper sheath into which very small diamonds (on the order of between 20 to 120 microns) are uniformly embedded. A nickel overstrike in the Superlok wire serves to further retain the cutting diamonds in the copper sheath.
The band saw technique discussed first above requires an endless loop saw blade band. Such an endless loop would be extremely efficient at cutting ingots. In addition, multi-loop band saws machines could be constructed to make simultaneous cuts and thus greatly shorten the processing time for these ingots. However, in order to accurately cut without significant kerf losses and scoring of the cut surfaces, an extremely fine wire saw loop would be required instead of a band, using a wire such as the diamond impregnated wire described in the previous paragraph.
Unfortunately, known attempts to make a suitable wire saw loop that can withstand the stresses of operation have all failed. These wire saw wires are extremely small diameter wires, on the order of 0.005-0.015 inch diameter wire. The formation of a wire loop requires welding the ends of the wire together. The welding of such wire materials together forms a brittle region at the weld, thus predisposing the wire loop to failure at the weld location. Conventional teachings require that the ends of the wire must be either shaped to have a slanted end surface so that the ends overlap in order to have a sufficient surface area at the weld location or shaped to provide blunted and rounded tips that are abutted and then melted together during the weld process. The overlapping and blunting results in a thickened, embrittled region at the weld which can bind in the saw kerf, leading to immediate wire breakage. Conventional annealing and heat treating of the weld leads to weakened wire strengths at the weld, again leading to premature failures. Thus an appropriate closed wire saw loop that can be used is lacking in the prior art. Attempts to fabricate a suitable wire loop in the past have all resulted in unacceptable breakage at the weld location. Consequently, closed wire saw loops are simply unknown in the semiconductor wafer manufacturing industry.
Therefore there is a need for diamond impregnated closed wire saw loop for use in cutting a work piece such as a semiconductor crystal ingot into thin, accurately cut wafers, an apparatus for such a saw loop, and a method of making such a wire saw loop that overcomes the above problems.
SUMMARY OF THE INVENTION
A method of forming a continuous or closed loop of wire having a plurality of cutting elements affixed thereto in accordance with the present invention comprises the steps of:
1) providing a steel wire having a tensile strength of at least 300,000 psi and having opposite ends;
2) butting the wire ends together;
3) welding the wire ends together creating a weld;
4) heating the welded wire ends and the weld to a temperature between 1450 F. and 1550 F. and allowing the welded ends and the weld to air cool;
5) removing excess weld material from the weld and the welded ends;
6) again heating the welded wire ends and the weld to a temperature between 1450 F. and 1550 F. and allowing the welded ends and the weld to air cool.
More preferably, the method according to the invention comprises the steps of:
1) providing a steel wire having a central wire axis and a tensile strength of at least 300,000 psi;
2) squaring each of the ends of the wire to form surfaces at right angles to the axis of the wire;
3) butting the end surfaces of the wire ends coaxially together;
4) applying an electrical current through the ends to electrically weld the ends of the wire together;
5) heating the welded together ends to about 1500 degrees Fahrenheit;
6) allowing the welded ends to air cool to less than about 500 degrees Fahrenheit;
7) removing excess weld material from the welded ends until the weld diameter substantially equals the wire diameter;
8) again heating the welded together ends to about 1500 degrees Fahrenheit followed by air cooling; and
9) affixing an abrasive material to the surface of the wire loop.
A wire endless loop in accordance with the present invention has a wire diameter of less than 0.020 inch and preferably between about 0.008 inch and 0.012 inch and is formed of a steel wire having a high tensile strength of at least 300,000 psi and a highly stable carbon matrix. One such steel is commonly known as “Carpenters Stainless Steel Type 321”. The wire loop abrasives are preferably fastened and distributed uniformly over the outer surface of the wire loop.
An apparatus for sectioning a semiconductor work piece in accordance with the invention preferably includes at least one continuous closed wire saw loop, a wire drive mechanism for moving the wire orthogonally with respect to the work piece longitudinal axis, a work piece rotation mechanism for rotating the workpiece about its axis, a wire advancing mechanism for positioning the wire from a first position proximate an outer diameter of the work piece to a second position proximate the axis of the work piece or inner diameter thereof. The wire saw loop continuously moves tangentially to the cut as the saw wire loop simultaneously advances through the work piece to its center or inner diameter, at which point the cut is complete. The apparatus may include a number of wire saw loops on the drive mechanism for making a like number of cuts simultaneously. The apparatus may also be configured as above but without a work piece rotation mechanism for those applications where tangential cutting of a work piece is not required.
Still further disclosed herein is a semiconductor wafer made by a process which comprises the steps of providing a continuous loop of wire having a plurality of cutting elements affixed thereto, continuously moving the wire loop orthogonally to a longitudinal axis of a crystalline semiconductor material ingot, rotating the ingot about its longitudinal axis and advancing the wire loop from a first position proximate an outer diameter of the ingot to a second position proximate an inner diameter thereof.
Other objects, features and advantages of the present invention will become apparent from a reading of the following detailed description when taken in conjunction with the accompanying drawing wherein a particular embodiment of the invention is disclosed as an illustrative example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified representational view of an apparatus for slicing a work piece, in particular a single crystal silicon ingot, in accordance with an exemplary implementation of the present invention;
FIG. 2 is a perspective view of a complete wire saw loop in accordance with the present invention;
FIG. 3 is an enlarged cross sectional view of the wire loop taken along the line 33 in FIG. 2.
FIGS. 4a through 4 e are sequential views of the weld formation method for the wire loop shown in FIGS. 2 and 3. Specifically,
FIG. 4a is a schematic side view of a pair of loop ends prior to squaring the ends.
FIG. 4b is a side view of the pair of loop ends of wire abutted together and placed in resistance welder clamps.
FIG. 4c is a side view as in 4 b after the ends are welded together.
FIG. 4d is a side view of the weld region after heat treatment in an annealing chamber.
FIG. 4e is a side view of the weld region after removal of excess weld material and following a second heat treatment in an annealing chamber.
DETAILED DESCRIPTION OF THE INVENTION
With reference now to FIG. 1, a simplified representational view of an apparatus 10 for slicing a generally cylindrical work piece, for example, a polysilicon or single crystal silicon, gallium arsenide (GaAs) or other crystalline ingot 14, is shown. The apparatus 10 comprises, in pertinent part, one or more cutting wire loops 12 made in accordance with the invention. Each of the wire saw loops 12 is utilized to accurately and rapidly crop and saw a generally cylindrical silicon ingot 14 into multiple silicon wafers for subsequent processing into discrete or integrated circuit devices.
The apparatus 10 includes a wire drive mechanism 16 for moving one or a plurality of wire saw loops 12 in a single direction as indicated by the arrow with respect to the longitudinal axis of the ingot 14. The wire drive mechanism 16, in the embodiment shown, drives a driven friction wheel 18 to move the wire around two guide pulleys 20 while tension is maintained by a tension pulley 22.
The apparatus 10 optionally further includes a work piece rotation mechanism 24, as shown, for rotating the ingot 14 about its longitudinal axis as the wire loop 12 is moved orthogonally with respect to the ingot 14. The work piece rotation mechanism 24, in the embodiment shown, may comprise one or more rotating collet fixtures 26 circumferentially surrounding the ingot 14 at positions along its length thereof. The collet fixtures 26, and hence the ingot 14, may be rotated by means of a number of drive rollers 28 or functionally equivalent elements. In an alternative embodiment, the ingot 14 may be secured to an end mounted work piece rotation mechanism 24 in lieu of the embodiment illustrated in this figure.
The apparatus 10 also includes a wire advancing mechanism 30 to which, in the embodiment illustrated, the wire drive mechanism 16 is mounted. The wire advancing mechanism 30 functions to advance the moving wire loop 12 from an initial position 32 displaced outwardly from, and proximate to, the outer diameter (“OD”) of the ingot 14 towards a final position 34 proximate the inner diameter (“ID”) of the ingot 14 to effectuate completion of a single cut. At this point, the motion of the wire advancing mechanism 30 may be reversed to withdraw the wire 12 back towards the initial position 32.
Alternatively, the wire advancing mechanism 30 may be configured to advance the moving wire loop 12 completely through the ingot 14 if the ingot rotating mechanism is not used. Also, in applications wherein repeated cuts or slices through the ingot 14 are desired, the apparatus 10 may further incorporate a work piece repositioning mechanism 36 to enable an indexed, translational repositioning of the ingot 14 to enable the wire 12 to make repeated cuts along its length, for example, to slice a number of wafers therefrom. In the embodiment of the apparatus shown in FIG. 1, the work piece repositioning mechanism 36 may include a programmably index driven lead screw 38 which reposition the work piece rotation mechanism 24 and ingot 14 as supported by a number of rollers 40 with respect to the wire saw 12. In alternative embodiments, the wire drive mechanism 16 and wire advancing mechanism 30 may be repositionable with respect to a generally fixed position work piece rotation mechanism 24.
The wire saw loop 12 is shown separately in FIG. 2 and in a sectional view in FIG. 3. With particular reference to FIG. 2, the wire saw loop 12 is made of a wire core 40 which has two ends 42 and 44 joined together by a weld 46. The wire core 40 of the loop 12 is made from carpenter stainless steel type 321. Carpenter Stainless Steel Type 321 is an austenitic chrome nickel steel. Metallurgical literature states that this steel should be annealed at 1750-1950 F. followed by water quench. According to the literature, stabilizing should be done at 1550 to 1650 F. Surprisingly, it has been found that this particular type of stainless steel, when fabricated into wire core 40 having a diameter of less than about 0.016 inches and a tensile strength of between 300,000 to 400,000 psi, and more preferably between 350,000 and 400,000 psi can be resistively welded together and conditioned at a temperature in a range between about 1450 F. to about 1550 F. and preferably at about 1500 F. to substantially return its characteristic properties at the weld location to a before weld condition. Thus the wire 40 at the weld 46 becomes as flexible and as strong as the remainder of the wire loop 12 when conditioned in accordance with the present invention.
It has also been experimentally determined that the wire end surfaces should be squared rather than slanted and abutted together at about right angles to the axis of the wire during the welding operation. Also, the heat treatment at elevated temperature must be performed twice, once before weld material removal and once after weld material removal.
The method of forming the wire loop 12 in accordance with the present invention basically comprises the following steps;
1) providing a steel wire having a tensile strength of at least 300,000 psi and having opposite ends 42 and 44 as shown in FIG. 4a;
2) butting the wire ends together as is shown in FIG. 4b;
3) welding the wire ends together creating a weld as shown in FIG. 4c;
4) heating the welded wire ends and the weld as shown in FIG. 4d to a temperature between 1450 F. and 1550 F. and allowing the welded ends and the weld to air cool;
5) removing excess weld material from the weld and the welded ends as shown in FIG. 4e;
6) again heating the welded wire ends and the weld to a temperature between 1450 F. and 1550 F. and allowing the welded ends and the weld to air cool.
More preferably, the method of forming the closed wire loop 12 comprises the steps of:
1) providing a piece of high strength stainless steel wire 40 having opposite ends 42 and 44 as shown in FIG. 4a,
2) squaring off each of the ends 42, 44 to form an end surface orthogonal to the axis through the wire 40;
3) placing the ends 42 and 44 of the wire 40 together abutting each other coaxially in a resistance welder 50;
4) applying an electrical current through the welder 50 effective to weld the abutting wire ends 42 and 44 together at temperatures in a range of 2100-3000 F. forming a weld 46;
5) placing the weld 46 and the welded ends 42 and 46 in a commercially available annealing chamber 52 such as a Microweld annealing chamber;
6) raising temperature in the annealing chamber and said welded ends to a temperature below the annealing temperature for Type 321 steel, between 1475 F. and 1525 F., and preferably about 1500 F. to heat treat the weld;
7) turn off the annealing chamber temperature control and allowing the chamber 52 and the weld 46 to cool to at least less than 500 F. and preferably to ambient temperature;
8) removing the welded ends 42 and 44 from the chamber 52 and removing excess weld material until the weld is substantially flush with, i.e. has the same diameter as the wire 40;
9) placing the welded ends 42 and 44 back in the annealing chamber 52;
10) raising temperature in the annealing chamber a second time to bring said welded ends 42, 44 and said weld 46 to a temperature below the annealing temperature for Type 321 steel, between 1475 F. and 1525 F., and preferably about 1500 F. to heat treat the weld a second time; and
11) allowing the chamber 52 and the weld 46 to cool naturally to at least 500 F. and preferably to ambient; and
12) removing the welded ends 42, 44 from the chamber 52
A closed loop of wire 40 formed by the above method is essentially as strong as the unwelded length of wire 40. The tensile strength of the unwelded wire 40 is between 300000 to 400000 psi and preferably around 375,000 to 400,000 psi. It has been experimentally found that for Carpenters' Steel Type 321, the optimum heat treatment temperature in the method of the present invention is about 1500 F. Temperatures substantially above this temperature cause premature weakening of the weld as do temperatures substantially below this temperature. There appears to be a Gaussian distribution of weld strengths close about this temperature of 1500 F. with a peak strength at 1500 F.
Referring now to FIGS. 4a through 4 e, the above sequence of steps is illustrated. In FIG. 4a, the raw ends 42 and 44 are shown prior to being squared and butted together in the welder clamps 48 as is shown in FIG. 4b. FIG. 4c shows the wire ends 42 and 44 welded together at weld 46, prior to the ends being removed from the welder 50. The welded ends 42 and 44 are next placed in an annealing oven 52 as shown in FIG. 4d. However, the weld 46 and the ends 42 and 44 are not annealed. The temperature of the oven 52 is simply raised to about 1500 F. and then turned off to allow the weld to cool to about 500 F. before the weld 46 is removed.
As shown in FIG. 4e, the excess weld material on weld 46 is ground away to leave the weld 46 flush with the surface of the wire 40. The weld 46 is then again placed in the oven 52 and temperature raised to about 1500 F. and then air cooled to below about 500 F. The closed loop of wire 40 is then removed and thoroughly allowed to cool to ambient temperature.
After formation of the wire loop as described above, the abrasive material is affixed to the wire loop. In the particular preferred embodiment shown in FIGS. 2 and 3, the wire saw loop 12 is formed with a coating of a metal 54 that is softer than the steel wire 40, such as copper or nickel. Preferably an electrolytic metal is such as copper or nickel is used. The layer of copper or nickel is electrolytically plated on the closed loop of wire 40 in an appropriate electrolytic bath and then industrial diamond particles 56 are mechanically impregnated into the layer or coating 54 to provide the abrasive substance on the wire saw loop 12. Finally, a thin layer 58 of nickel, of preferably about 0.0002 to 0.0005 inch thickness is electroplated over the entire structure to help seat the diamond abrasive particles 56.
For example, a wire diameter of about 0.012 inch, the copper or nickel coating 54 with diamonds 56 mechanically impregnated therein has a thickness of about 0.002 inch to yield an overall wire saw diameter of about 0.016 inch.
Other methods of adhering abrasives such as diamond particles 56 or other hard materials such as tungsten carbide to the wire 40 could also be utilized in the present invention. For example, an adhesive bonding agent may be applied to the wire and the abrasive materials bonded to the adhesive bonding agent. In this case, the glue or bonding agent would be applied to the wire surface and then the wire loop rolled through an abrasive powder.
While there have been described above the principles of the present invention in conjunction with specific apparatus and wire sawing techniques, it is to be clearly understood that the foregoing description is made only by way of example and not as a limitation to the scope of the invention. Particularly, it is recognized that the teachings of the foregoing disclosure will suggest other modifications to those persons skilled in the relevant art. Such modifications may involve other features which are already known per se and which may be used instead of or in addition to features already described herein. Although claims have been formulated in this application to particular combinations of features, it should be understood that the scope of the disclosure herein also includes any novel feature or any novel combination of features disclosed either explicitly or implicitly or any generalization or modification thereof which would be apparent to persons skilled in the relevant art, whether or not such relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as confronted by the present invention. The applicants hereby reserve the right to formulate new claims to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

Claims (21)

What is claimed is:
1. A method for sectioning a substantially cylindrical crystalline work piece comprising the steps of:
providing a continuous wire loop having a plurality of cutting elements affixed thereto;
moving said wire orthogonally to a longitudinal axis of said work piece continuously in one direction; and
advancing said wire from a first position proximate an outer diameter of said work piece to a second position at least proximate said longitudinal axis.
2. The method of claim 1 wherein said step of providing is carried out by means of a diamond impregnated closed wire loop.
3. The method of claim 1 wherein said step of moving is carried out by the step of:
linearly drawing said wire in one direction with respect to said longitudinal axis of said work piece.
4. The method of claim 1 wherein said steps of providing and moving further comprise the steps of:
providing a plurality of wire loops in a generally parallel and spaced apart relationship therebetween, each of said wire loops having a plurality cutting elements affixed thereto; and
simultaneously moving said plurality of wires orthogonally to a longitudinal axis of said work piece.
5. An apparatus for sectioning a substantially cylindrical crystalline work piece comprising:
at least one continuous closed wire loop having a plurality of cutting elements affixed thereto;
a wire drive mechanism for moving said wire orthogonally with respect to a longitudinal axis of said work piece;
a work piece rotation mechanism coupled to said work piece for rotating said work piece about said longitudinal axis; and
a wire advancing mechanism for positioning said wire from a first position proximate an outer diameter of said work piece to a second position proximate an inner diameter thereof.
6. The apparatus of claim 5 wherein said wire loop comprises a plurality of diamonds impregnated in said wire.
7. The apparatus of claim 6 wherein said wire loop comprises a steel core having a circumferentially surrounding copper sheath.
8. The apparatus of claim 7 wherein said plurality of diamonds are impregnated in said copper sheath.
9. The apparatus of claim 8 wherein said wire further comprises a nickel layer overlying said copper sheath.
10. The apparatus of claim 8 wherein said plurality of diamonds are substantially uniformly distributed about a circumference and length of said wire.
11. The apparatus of claim 5 wherein said wire drive mechanism is operative to linearly draw said wire in one direction with respect to said longitudinal axis of said work piece.
12. The apparatus of claim 11 wherein said wire comprises a closed loop of wire.
13. A wire saw loop comprising:
a wire core having a diameter of less than 0.020 inches and a tensile strength of at least 300,000 psi, wherein the wire core has a coating of electrolytic metal and a distributed plurality of abrasives adhered to said coating, and further wherein the wire core has a first and a second end each with a surface substantially orthogonal to an axis of the wire core and wherein the first and second ends are positioned coaxially in substantially abutting contact; and
a weld between the first and second ends adjoining the first and second ends, wherein the weld has a diameter less than about the diameter of the wire core and a tensile strength of at least about the tensile strength of the wire core.
14. The saw loop according to claim 13 wherein said abrasives are industrial diamonds.
15. The saw loop according to claim 14 wherein said industrial diamonds are mechanically impregnated into said coating of electrolytic metal.
16. The saw loop according to claim 13 wherein said wire core has a diameter between about 0.008 inches and 0.016 inches.
17. The saw loop according to claim 16 further comprising a nickel overcoating over at least a portion of said diamonds and said electrolyte metal coating.
18. The saw loop according to claim 13, wherein the weld is formed by applying an electrical current to the first and second ends to achieve a temperature between about 2100 and 3000° F.
19. The saw loop according to claim 18, wherein the weld is formed by heat treating in the range of about 1475 to 1525° F.
20. A semiconductor wafer made by a process comprising the steps of:
providing a closed wire saw loop having a plurality of cutting elements affixed thereto;
moving said wire continuously in one direction orthogonally to a longitudinal axis of a crystalline semiconductor material ingot;
rotating said ingot about said longitudinal axis; and
advancing said wire from a first position proximate an outer diameter of said ingot through said ingot to a second position proximate at least a center of said ingot.
21. The semiconductor wafer of claim 20 wherein said step of providing is carried out by means of a diamond impregnated wire.
US09/467,510 1997-11-28 1999-12-20 Continuous wire saw loop and method of manufacture thereof Expired - Fee Related US6311684B1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US08/980,386 US6065462A (en) 1997-11-28 1997-11-28 Continuous wire saw loop and method of manufacture thereof
US09/467,510 US6311684B1 (en) 1997-11-28 1999-12-20 Continuous wire saw loop and method of manufacture thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US09/467,510 US6311684B1 (en) 1997-11-28 1999-12-20 Continuous wire saw loop and method of manufacture thereof

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US08/980,386 Division US6065462A (en) 1997-11-28 1997-11-28 Continuous wire saw loop and method of manufacture thereof

Publications (1)

Publication Number Publication Date
US6311684B1 true US6311684B1 (en) 2001-11-06

Family

ID=25527522

Family Applications (2)

Application Number Title Priority Date Filing Date
US08/980,386 Expired - Fee Related US6065462A (en) 1997-11-28 1997-11-28 Continuous wire saw loop and method of manufacture thereof
US09/467,510 Expired - Fee Related US6311684B1 (en) 1997-11-28 1999-12-20 Continuous wire saw loop and method of manufacture thereof

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US08/980,386 Expired - Fee Related US6065462A (en) 1997-11-28 1997-11-28 Continuous wire saw loop and method of manufacture thereof

Country Status (2)

Country Link
US (2) US6065462A (en)
WO (1) WO1999028075A2 (en)

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6637305B2 (en) 2002-02-07 2003-10-28 William Crockford Apparatus for machining composite material test specimens
CN100421865C (en) * 2005-10-12 2008-10-01 博深工具股份有限公司 Method for making diamond string beads
US20100006082A1 (en) * 2008-07-11 2010-01-14 Saint-Gobain Abrasives, Inc. Wire slicing system
US20100170495A1 (en) * 2007-10-30 2010-07-08 Pall Corporation Method and system for manufacturing wafer-like slices from a substrate material
WO2010099779A2 (en) 2009-03-02 2010-09-10 Dirk Haussmann Method and apparatus for welding wires
DE102009011036A1 (en) 2009-03-02 2010-09-16 Haussmann, Dirk Device for welding wires by light source, has welded wires which are guided and welded together by guiding devices, where tube is glass tube, glass ceramic tube and ceramic tube
US20100319673A1 (en) * 2003-01-24 2010-12-23 Gemini Saw Company Blade ring saw blade
US20110045292A1 (en) * 2009-08-14 2011-02-24 Saint-Gobain Abrasives, Inc. Abrasive articles including abrasive particles bonded to an elongated body, and methods of forming thereof
CN104369274A (en) * 2014-11-17 2015-02-25 福州天石源超硬材料工具有限公司 Horizontal loop line cutting machine with cantilever
US9067268B2 (en) 2009-08-14 2015-06-30 Saint-Gobain Abrasives, Inc. Abrasive articles including abrasive particles bonded to an elongated body
WO2015145024A1 (en) 2014-03-24 2015-10-01 Thermocompact Method for manufacturing a closed loop of cutting wire
US9186816B2 (en) 2010-12-30 2015-11-17 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9211634B2 (en) 2011-09-29 2015-12-15 Saint-Gobain Abrasives, Inc. Abrasive articles including abrasive particles bonded to an elongated substrate body having a barrier layer, and methods of forming thereof
US9254552B2 (en) 2012-06-29 2016-02-09 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9278429B2 (en) 2012-06-29 2016-03-08 Saint-Gobain Abrasives, Inc. Abrasive article for abrading and sawing through workpieces and method of forming
US9375826B2 (en) 2011-09-16 2016-06-28 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9409243B2 (en) 2013-04-19 2016-08-09 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9878382B2 (en) 2015-06-29 2018-01-30 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9902044B2 (en) 2012-06-29 2018-02-27 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US10647017B2 (en) 2017-05-26 2020-05-12 Gemini Saw Company, Inc. Fluid-driven ring saw

Families Citing this family (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6279564B1 (en) * 1997-07-07 2001-08-28 John B. Hodsden Rocking apparatus and method for slicing a workpiece utilizing a diamond impregnated wire
US6273288B1 (en) * 1999-04-28 2001-08-14 Cambro Manufacturing Company Food pan and cover with interior hinged lid
DE19959414A1 (en) * 1999-12-09 2001-06-21 Wacker Chemie Gmbh Device for simultaneously separating number of discs from workpiece has framesaw with number of individual wires and device for holding workpiece and turning it about longitudinal axis
US6418921B1 (en) 2001-01-24 2002-07-16 Crystal Systems, Inc. Method and apparatus for cutting workpieces
US6719188B2 (en) 2001-07-24 2004-04-13 International Business Machines Corporation Rework methods for lead BGA/CGA
US6846726B2 (en) * 2002-04-17 2005-01-25 Lam Research Corporation Silicon parts having reduced metallic impurity concentration for plasma reaction chambers
US8291895B2 (en) * 2007-09-05 2012-10-23 University Of South Carolina Methods, wires, and apparatus for slicing hard materials
US8286625B2 (en) 2008-05-27 2012-10-16 Jenkins Nicholas J T Underwater diamond wire saw assembly
KR20120102679A (en) * 2009-11-05 2012-09-18 가부시키가이샤 나카무라초코 Super-abrasive grain fixed type wire saw, and method of manufacturing super-abrasive grain fixed type wire saw
US8651098B2 (en) * 2010-03-04 2014-02-18 MacTech, Inc. Apparatus, system and method for using a diamond-impregnated wire to cut an object
EP2566801A2 (en) * 2010-05-04 2013-03-13 NV Bekaert SA Fixed abrasive sawing wire with removable protective coating
CN102211231A (en) * 2011-05-19 2011-10-12 曹玮 Sand feeding and thickening electroplating equipment for long diamond wire saw
DE102011112270B4 (en) * 2011-09-05 2014-01-09 Dirk Haussmann Device for separating an ingot into ingot sections
CN102352523B (en) * 2011-11-09 2014-07-02 长沙岱勒新材料科技股份有限公司 Heat treatment method for electroplated diamond wire saw
FR2988023A1 (en) * 2012-03-16 2013-09-20 Sodetal Sas SAW WIRE, METHOD FOR MANUFACTURING SUCH WIRE, AND USE
US9776265B2 (en) 2013-06-03 2017-10-03 MacTech, Inc. System, method and retractable and/or folding apparatus for cutting an object
US9636761B2 (en) 2013-07-25 2017-05-02 MacTech, Inc. Modular cutting system, method and apparatus
JP6249319B1 (en) * 2017-03-30 2017-12-20 パナソニックIpマネジメント株式会社 Saw wire and cutting device
US10403595B1 (en) * 2017-06-07 2019-09-03 United States Of America, As Represented By The Secretary Of The Navy Wiresaw removal of microelectronics from printed circuit board
JP6751900B2 (en) * 2018-01-29 2020-09-09 パナソニックIpマネジメント株式会社 Metal wire and saw wire

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE29491E (en) * 1973-05-18 1977-12-13 Helen E. Snow Method of making a cable-type saw
US4384564A (en) * 1981-01-22 1983-05-24 Crystal Systems Inc. Process of forming a plated wirepack with abrasive particles only in the cutting surface with a controlled kerf
US4674474A (en) * 1986-08-06 1987-06-23 Engelhard Corporation Stone cutting wire saw
US4856490A (en) * 1987-09-09 1989-08-15 Osaka Diamond Industrial Co., Ltd. Wire saw
US4907564A (en) * 1987-11-24 1990-03-13 Sumitomo Rubber Industries, Ltd. Wire saw
US5616065A (en) * 1995-03-23 1997-04-01 Wacker Siltronic Gesellschft fur Halbleitermaterialien Aktiengesellschaft Wire saw and method for cutting wafers from a workpiece
US5628301A (en) * 1995-07-14 1997-05-13 Tokyo Seimitsu Co., Ltd. Wire traverse apparatus of wire saw

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4922B1 (en) * 1970-02-03 1974-01-05
IT1236762B (en) * 1988-10-28 1993-04-02 HELICAL ROPE WITH DIAMOND CUTTER.
US4911209A (en) * 1989-03-15 1990-03-27 Expo Wire Company Method and apparatus for forming wire mesh cages
US5181503A (en) * 1991-06-26 1993-01-26 W. F. Meyers Company, Inc. Stone slab saw
AT402032B (en) * 1991-07-17 1997-01-27 Evg Entwicklung Verwert Ges MACHINE FOR THE PROCESSING OF GRID MATS FROM LENGTHED AND CROSSWIRE WELDED TOGETHER
JP3427956B2 (en) * 1995-04-14 2003-07-22 信越半導体株式会社 Wire saw equipment
US5878737A (en) * 1997-07-07 1999-03-09 Laser Technology West Limited Apparatus and method for slicing a workpiece utilizing a diamond impregnated wire

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE29491E (en) * 1973-05-18 1977-12-13 Helen E. Snow Method of making a cable-type saw
US4384564A (en) * 1981-01-22 1983-05-24 Crystal Systems Inc. Process of forming a plated wirepack with abrasive particles only in the cutting surface with a controlled kerf
US4674474A (en) * 1986-08-06 1987-06-23 Engelhard Corporation Stone cutting wire saw
US4856490A (en) * 1987-09-09 1989-08-15 Osaka Diamond Industrial Co., Ltd. Wire saw
US4907564A (en) * 1987-11-24 1990-03-13 Sumitomo Rubber Industries, Ltd. Wire saw
US5616065A (en) * 1995-03-23 1997-04-01 Wacker Siltronic Gesellschft fur Halbleitermaterialien Aktiengesellschaft Wire saw and method for cutting wafers from a workpiece
US5628301A (en) * 1995-07-14 1997-05-13 Tokyo Seimitsu Co., Ltd. Wire traverse apparatus of wire saw

Cited By (39)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6637305B2 (en) 2002-02-07 2003-10-28 William Crockford Apparatus for machining composite material test specimens
US20100319673A1 (en) * 2003-01-24 2010-12-23 Gemini Saw Company Blade ring saw blade
US8286624B2 (en) * 2003-01-24 2012-10-16 Gemini Saw Company, Inc. Blade ring saw blade
CN100421865C (en) * 2005-10-12 2008-10-01 博深工具股份有限公司 Method for making diamond string beads
US20100170495A1 (en) * 2007-10-30 2010-07-08 Pall Corporation Method and system for manufacturing wafer-like slices from a substrate material
US8056551B2 (en) * 2007-10-30 2011-11-15 Pall Corporation Method and system for manufacturing wafer-like slices from a substrate material
WO2010006148A2 (en) * 2008-07-11 2010-01-14 Saint-Gobain Abrasives. Inc. Wire slicing system
WO2010006148A3 (en) * 2008-07-11 2010-05-20 Saint-Gobain Abrasives, Inc. Wire slicing system
US20100006082A1 (en) * 2008-07-11 2010-01-14 Saint-Gobain Abrasives, Inc. Wire slicing system
WO2010099779A3 (en) * 2009-03-02 2011-01-13 Dirk Haussmann Method and apparatus for welding wires, including an annealing process prior to, during, or following the welding process; wire produced; use of small tubes in said method
DE102009011037A1 (en) 2009-03-02 2010-09-16 Dirk Haussmann Method and device for welding wires
DE102009011036B4 (en) * 2009-03-02 2011-02-17 Haussmann, Dirk Apparatus and method for welding wires
DE102009011036A1 (en) 2009-03-02 2010-09-16 Haussmann, Dirk Device for welding wires by light source, has welded wires which are guided and welded together by guiding devices, where tube is glass tube, glass ceramic tube and ceramic tube
WO2010099779A2 (en) 2009-03-02 2010-09-10 Dirk Haussmann Method and apparatus for welding wires
CN102341210A (en) * 2009-03-02 2012-02-01 德克·豪斯曼 Method and apparatus for welding wires, including an annealing process prior to, during, or following the welding process, wires, and application of small pipe in the method
DE102009011037B4 (en) * 2009-03-02 2012-03-15 Dirk Haussmann Method and device for welding wires
CN102341210B (en) * 2009-03-02 2016-03-23 德克·豪斯曼 For by before welding, period or annealing afterwards carrys out the method and apparatus of welding wire; Manufactured wire rod; In the method to the application of tubule
US20110045292A1 (en) * 2009-08-14 2011-02-24 Saint-Gobain Abrasives, Inc. Abrasive articles including abrasive particles bonded to an elongated body, and methods of forming thereof
US9862041B2 (en) 2009-08-14 2018-01-09 Saint-Gobain Abrasives, Inc. Abrasive articles including abrasive particles bonded to an elongated body
US9028948B2 (en) 2009-08-14 2015-05-12 Saint-Gobain Abrasives, Inc. Abrasive articles including abrasive particles bonded to an elongated body, and methods of forming thereof
US9067268B2 (en) 2009-08-14 2015-06-30 Saint-Gobain Abrasives, Inc. Abrasive articles including abrasive particles bonded to an elongated body
US9186816B2 (en) 2010-12-30 2015-11-17 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9248583B2 (en) 2010-12-30 2016-02-02 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9375826B2 (en) 2011-09-16 2016-06-28 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9211634B2 (en) 2011-09-29 2015-12-15 Saint-Gobain Abrasives, Inc. Abrasive articles including abrasive particles bonded to an elongated substrate body having a barrier layer, and methods of forming thereof
US9254552B2 (en) 2012-06-29 2016-02-09 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9278429B2 (en) 2012-06-29 2016-03-08 Saint-Gobain Abrasives, Inc. Abrasive article for abrading and sawing through workpieces and method of forming
US10596681B2 (en) 2012-06-29 2020-03-24 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9902044B2 (en) 2012-06-29 2018-02-27 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9687962B2 (en) 2012-06-29 2017-06-27 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US9409243B2 (en) 2013-04-19 2016-08-09 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
WO2015145024A1 (en) 2014-03-24 2015-10-01 Thermocompact Method for manufacturing a closed loop of cutting wire
US10086453B2 (en) 2014-03-24 2018-10-02 Thermocompact Process for manufacturing a closed loop of cutting wire
CN104369274B (en) * 2014-11-17 2016-04-13 福州天石源超硬材料工具有限公司 Cantilever horizontal loop cutting machine
CN104369274A (en) * 2014-11-17 2015-02-25 福州天石源超硬材料工具有限公司 Horizontal loop line cutting machine with cantilever
US9878382B2 (en) 2015-06-29 2018-01-30 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US10137514B2 (en) 2015-06-29 2018-11-27 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US10583506B2 (en) 2015-06-29 2020-03-10 Saint-Gobain Abrasives, Inc. Abrasive article and method of forming
US10647017B2 (en) 2017-05-26 2020-05-12 Gemini Saw Company, Inc. Fluid-driven ring saw

Also Published As

Publication number Publication date
WO1999028075A3 (en) 1999-08-05
WO1999028075A2 (en) 1999-06-10
US6065462A (en) 2000-05-23

Similar Documents

Publication Publication Date Title
US6311684B1 (en) Continuous wire saw loop and method of manufacture thereof
US5878737A (en) Apparatus and method for slicing a workpiece utilizing a diamond impregnated wire
US6295977B1 (en) Method and device for simultaneously cutting off a multiplicity of wafers from a workpiece
KR101715565B1 (en) Method for simultaneously cutting a multiplicity of slices of particularly uniform thickness from a workpiece
US6543434B2 (en) Device for simultaneously separating a multiplicity of wafers from a workpiece
EP1371467B1 (en) Wire saw and method of slicing a cylindrical workpiece
TWI556933B (en) Method for simultaneously cutting a multiplicity of wafers from a workpiece
JP3427956B2 (en) Wire saw equipment
TWI284073B (en) Wire saw
JPH05192816A (en) Method of manufacturing seamless strip loop and wire loop and its device, use of said loops as cutting tool of band saw and wire saw
JPH09248719A (en) Cutting method and device of semiconductor ingot for epitaxial wafer semiconductor
JP3325676B2 (en) Slicing method of silicon ingot
US6024080A (en) Apparatus and method for slicing a workpiece utilizing a diamond impregnated wire
EP1009569A2 (en) Apparatus and method for slicing a workpiece utilizing a diamond impregnated wire
US5799644A (en) Semiconductor single crystal ingot cutting jig
KR20050012938A (en) apparatus for slicing ingot
JP3205718B2 (en) Wire saw cutting method and device
US20030181023A1 (en) Method of processing silicon single crystal ingot
JP5821679B2 (en) Cutting method of hard and brittle ingot
JP2005059164A (en) Electro-deposition band saw
JPH10217239A (en) Slicing method and wire sawing device
US20020033171A1 (en) Holding unit for semiconductor wafer sawing
EP0781619A1 (en) Method of making silicone carbide wafers from silicon carbide bulk crystals
JP2003109917A (en) Method of manufacturing semiconductor wafer, method of cutting single-crystal ingot, cutting device, and holding jig
CN210256793U (en) Large-size silicon carbide wafer diamond wire cutting machine tool

Legal Events

Date Code Title Description
FPAY Fee payment

Year of fee payment: 4

REMI Maintenance fee reminder mailed
SULP Surcharge for late payment

Year of fee payment: 7

FPAY Fee payment

Year of fee payment: 8

AS Assignment

Owner name: LASER TECHNOLOGY WEST, LTD., COLORADO

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HODSDEN, JOHN B.;HODSDEN, JEFFREY BURGESS;REEL/FRAME:023498/0341

Effective date: 19980403

AS Assignment

Owner name: LASER TECHNOLOGY WEST, LLC, COLORADO

Free format text: CHANGE OF NAME;ASSIGNOR:LASER TECHNOLOGY WEST, LTD.;REEL/FRAME:023510/0086

Effective date: 19990101

AS Assignment

Owner name: DIAMOND WIRE TECHNOLOGY LLC, COLORADO

Free format text: CHANGE OF NAME;ASSIGNOR:LASER TECHNOLOGY WEST, LLC;REEL/FRAME:023510/0533

Effective date: 20060222

AS Assignment

Owner name: SNOW ACQUISITION CORP., SWITZERLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:DIAMOND WIRE TECHNOLOGY LLC;REEL/FRAME:023525/0248

Effective date: 20090914

AS Assignment

Owner name: DIAMOND WIRE TECHNOLOGY, INC., SWITZERLAND

Free format text: CHANGE OF NAME;ASSIGNOR:SNOW ACQUISITION CORP.;REEL/FRAME:023538/0929

Effective date: 20090914

AS Assignment

Owner name: DIAMOND MATERIALS TECH, INC., COLORADO

Free format text: CHANGE OF NAME;ASSIGNOR:DIAMOND WIRE TECHNOLOGY, INC.;REEL/FRAME:025204/0778

Effective date: 20091228

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Expired due to failure to pay maintenance fee

Effective date: 20131106